The present invention generally relates to intravascular devices. More specifically, the present invention relates to intravascular stent delivery catheters and methods of use.
Intravascular stents are commonly used to maintain patency of a vascular lumen, particularly after an angioplasty (e.g., PTCA or PTA) or an atherectomy procedure. Intravascular stents come in a wide variety of designs, but typically comprise a metallic expandable structure, and are usually either self-expanding or balloon-expandable. Intravascular stents are typically delivered and deployed utilizing a stent delivery catheter such as a balloon catheter. The stent delivery catheter is advanced over a guidewire through a guide catheter, and with the assistance of radiographic fluoroscopy, is navigated to the desired treatment site.
In most instances, the desired treatment site is located well within a vascular lumen distal of the corresponding ostium. In other instances, the treatment site is located in the vascular lumen immediately adjacent the ostium. For example, in coronary applications, the treatment site may be located in the right coronary artery (RCA) immediately adjacent the ostium in the aortic wall. In such instances, it is often difficult to precisely position the intravascular stent such that the stent is completely within the vascular lumen and as close as possible to the ostium. In other words, it is very difficult using conventional radiographic fluoroscopic techniques to position the stent in the vascular lumen adjacent the ostium without having a portion of the stent extending proximal of the ostium.
If any portion of the intravascular stent is placed proximal of the ostium, the protruding portion of the stent may initiate a thrombogenic response potentially creating a distal embolism. For example, in coronary applications, a stent protruding into the lumen of the ascending aorta may cause an embolism to form in the cerebral vasculature potentially resulting in a stroke. Accordingly, because of the limitations associated with conventional stent delivery catheters and radiographic fluoroscopic visualization techniques, there is a substantial unmet need for an improved device and method for precisely positioning an intravascular stent in a vascular lumen adjacent the corresponding ostium.
To satisfy this substantial unmet need, the present invention provides a stent positioning device and associated method for precisely delivering and deploying an intravascular stent in a vascular lumen adjacent the ostium thereof. The present invention may be utilized for both coronary and peripheral vascular applications. The stent positioning device is slidably disposed about a stent delivery catheter and includes a distally disposed expandable member having an expanded diameter that is larger than the vascular lumen adjacent the ostium. The stent positioning device is positioned in the vasculature such that the distal end of the expandable member engages the ostium. The stent delivery catheter is positioned such that the proximal end of the stent is positioned adjacent the distal end of the expandable member by using either a visible marker on the stent delivery catheter or a radiopaque marker on the expandable member. When the proximal end of the stent is positioned adjacent the distal end of the expandable member, the stent may be deployed such that the proximal end of the stent is precisely located in the vascular lumen adjacent the ostium.
In the visible marker embodiment, the stent delivery catheter includes a visible marker disposed on the proximal portion of the shaft. The proximal visible marker is separated from the proximal end of the distally disposed stent by a length equal to the overall length of the stent positioning device. With this arrangement, the proximal end of the stent may be precisely located in the vascular lumen adjacent the ostium when the proximal end of the stent positioning device is located at the visible marker and the distal end of the expandable member engages the ostium.
In the radiopaque expandable member embodiment, the distal end of the expandable member is radiopaque or includes a radiopaque marker disposed thereon. The proximal end of the stent may be precisely located in the vascular lumen adjacent the ostium by utilizing radiographic techniques to position the proximal end of the stent at the distal end of the expandable member when the distal end of the expandable member engages the ostium.
In a preferred embodiment, the present invention provides a method including the initial step of placing the stent positioning device about the stent delivery catheter, which may be performed by the physician or by the manufacturer of the stent delivery catheter. The stent delivery catheter with the stent disposed thereon is inserted and navigated through the vasculature, across the ostium and into the vascular lumen to be treated, with the distal end of the expandable member disposed proximal of the ostium. The expandable member is then expanded and advanced until the distal end thereof engages the ostium. The stent delivery catheter is then retracted in the proximal direction until the proximal end of the stent is positioned adjacent the distal end of the expandable member. This may be accomplished by utilizing a visible marker on the proximal portion of the stent delivery catheter as described previously. Alternatively, this may be accomplished by providing a radiopaque distal end on the expandable member and using radiographic visualization techniques. The stent may then be deployed such that the proximal end of the stent is located in the vascular lumen immediately adjacent the ostium.